Adrenoreceptors, or adrenergic receptors, are sites on effector organs that are innervated by postganglionic adrenergic fibers of the sympathetic nervous system, and are classified as either alpha-adrenergic or beta-adrenergic receptors. Alpha-adrenergic receptors respond to norepinephrine and to such blocking agents as phenoxybenzamine and phentolamine, whereas beta-adrenergic receptors respond to epinephrine and to such blocking agents as propranolol.
Beta-adrenergic receptors are sub-classified as beta-1, beta-2, and beta-3 adrenoreceptors. Generally, beta-1 stimulation causes cardiostimulation, whereas beta-2 stimulation causes bronchodilation and vasodilation.
Beta-3 receptors are found on the cell surface of both white and brown adipocytes where their stimulation promotes both lipolysis and energy expenditure. Agonists of beta-3 adrenoreceptors are known to be useful in the treatment of hyperglycemia (diabetes) and obesity in mammals, as well as in the treatment of gastrointestinal disorders and neurogenetic inflammation (U.S. Pat. No. 5,561,142). Additionally, they are known to lower triglyceride and cholesterol levels and to raise high-density lipoprotein levels in mammals (U.S. Pat. No. 5,451,677). Accordingly, they are useful in the treatment of conditions such as hypertriglyceridemia, hypercholesterolemia, and in lowering high-density lipoprotein levels. They also may be useful in treating patients with Syndrome X, impaired fasting glucose, and/or impaired glucose tolerance, as well as in the treatment of atherosclerotic and cardiovascular diseases and related conditions.
Additionally, it is also believed that the compounds of this invention are effective in the treatment of ocular hypertension and glaucoma, and in the treatment of urinary disorders including pollakiuria and incontinence, as well as in the treatment of prostate disease and as topical anti-inflammatory agents.
It has now been found that certain novel chroman derivatives are effective as beta-3 agonists and are useful in the treatment of beta-3 adrenoreceptor-mediated conditions.